Inspirator burner



y 26, 0 H. G. VAN ROOYEN 3,514,041

INSPIRATOR BURNER Filed April 24, 1967 INVENTOR HARVEY G. VAN ROOYEN ATTORNEY 3,514,041 INSPIRATOR BURNER Harvey G. Van Rooyen, Westminster, Col0., assignor to Denver Fireclay Company, Denver, Colo., a corporation of Delaware Filed Apr. 24, 1967, Ser. No. 639,920 Int. Cl. B05b 7/08 US. Cl. 239427.3 6 Claims ABSTRACT OF THE DISCLOSURE The burner is of the inspirator type characterized by an outer venturi-shaped shell, or primary inspirator, a gas discharge orifice located at the base of the shell, and a slotted burner tube is located for upward projection from the orifice through the throat region of the shell to improve the flame characteristics and promote optimum combustion over a wide temperature range, but with particular reference to solving difficulties of proper combustion in the lower temperature and pressure range.

This invention relates to a novel and improved burner construction and more particularly relates to an improved burner of the inspirator type which is especially adaptable for use either individually or in series for heating a kiln 'over a wide, predictable temperature range.

In the kiln art, the kiln must be gradually raised to operating temperature and gradually cooled to room temperature and in accordance with well-known practice this is best done by following an optimum or selected temperature curve for the ware being heated. In the past, particular problems have been encountered in the preheat or lower temperature ranges where at a lower gas pressure it is difiicult to establish the proper flame characteristics and to proportion the air/ gas mixture for most efficient heating. Further difficulties have been encountered in maintaining the proper air/ gas mixture over the entire operating range as well as to establish the proper flame height and characteristics for maximum heating and to accomplish same with minimum heat loss; yet it is highly desirable to retain the inherent simplicity of the gas burner and in such a way that the burner is self-regulating over the entire heat range in achieving the optimum flame characteristics and thorough mixing of the gas and air without separate means of control.

Accordingly, it is an object of the present invention to overcome the foregoing disadvantages and difficulties encountered in the prior art by making provision for a novel and improved gas burner which is self-regulating to permit accurate control of the flame characteristics and gas/ air mixture over a wide temperature range, especially at lower temperatures and gas pressures.

It is another object of the present invention to provide for a novel and improved burner of the inspirator type which avoids candling of the flame particularly in the lower temperature range and promotes thorough, intimate mixing of the gas and air for optimum combustion throughout the length of the burner.

It is a further object of the present invention to provide an inspirator burner conformable for use in heating ware in a kiln wherein the burner is self-regulating to establish the optimum gas/ air mixture and flame characteristics over the entire operating range of the kiln and eliminates a separate preheat cycle as well as separate means of control of the gas/ air mixture.

The above and other objects, advantages and features will become more readily appreciated and understood from a consideration of the following detailed description when taken together with the accompanying drawings, in which:

FIG. 1 is a cross sectional view of a preferred form of inspirator burner.

United States Patent 0 3,514,041 Patented May 26, 1970 "Ice FIG. 2 is a bottom plan view of the base of the burner; and

FIG. 3 is a sectional view taken on line 33 of FIG. 1.

Referring in more detail to the drawings, there is shown in FIGS. 1 to 3 a preferred form of inspirator burner being broadly comprised of an outer shell or casing 10, a spud or other suitable form of fitting 12 mounted in the base of the shell for connection to a source of gas supply, the spud terminating at its upper end in an orifice member 14, and a burner tube 16 is mounted in surrounding relation to the orifice 14.

One important feature of the present invention resides in the disposition and relation of the outer shell 10, or primary inspirator, to the burner orifice 14 and tube 16. Here the shell 10 is venturi-shaped and is provided with a relatively large, open circular base 20 having a centrally located ring 21 intermediately between radial flanges 22. The ring defines a circular opening 23 for insertion and mounting of the spud 12, and inlet openings 25 between the radial flanges 22 serve to draw outside air upwardly through the openings for mixture with the gas discharged from the orifice 14.

From the base 20, the shell converges or tapers sharply inwardly to define a generally concave or curved wall section 26 terminating in a restricted throat region 28 then gradually diverges upwardly to define a relatively straight conical wall section 30, circular in cross section, terminating in an upper relatively flat circular edge 32. It will be seen that the relatively straight conical wall section 30 is elongated with respect to the lower curved wall section 26 and for example is on the order of three to four times the length of the shell from the throat region to the base 20.

The fitting 12 is in the form of a hollow generally cylindrical body interconnected between the orifice member 14 and a suitable source of gas supply, not shown. The fitting may suitably include a relatively thick-walled hollow body portion 34 having an outer hexagonal surface 35 to facilitate engagement by a Wrench or other tool with a lower extension 36 being externally threaded for connection to a gas supply pipe, not shown. In addition an upper cylindrical extension 38 of reduced diameter is dimensioned for insertion in press-fit relation upwardly through the central opening 23 of the ring 21. The fitting is provided with a central longitudinal bore or passage 40 etxending the length thereof, and the upper cylindrical extension 38 is internally threaded at the exit end of the bore for threaded connection of the male end 42 of the body of the orifice member 14. In this connection, the orifice is provided with a hollow body 44 having an exr ternal surface 45 of hexagonal shape to permit engagement and turning by a suitable tool for threaded connection to the upper end of the fitting, and the upper terminal end of the orifice has an upper convergent inner wall surface 46 terminating in a limited discharge orifice 48 through which the gas will escape at a relatively high velocity.

The burner tubing 16 is relatively thin-walled and elongated for upward projection from the upper end of the orifice through the throat region 28 of the shell. The tubing is formed with a lower end 50 sized for press-fit insertion of the external surface 45 of the orifice body, and a series of longitudinal slots 52 are formed at spaced circumferential intervals in the wall of the tubing directly above the upper end of the discharge orifice 48. In this relation the burner tube 16 functions as secondary inspirator and particularly in the lower temperature ranges, such as, from ambient temperatures to 300 P. will cooperate with the outer casing, or primary inspirator to avoid candling or dispersion of the flame, or in other words, to lengthen and intensify the flame whereby to increase its velocity and induce the upward flow of combustion air in and around the tube. Moreover, im-

proved flame characteristics are maintained by projecting the burner tube upwardly to a point at or somewhat above the narrow portion of the throat. In this way the air pass ing upwardly through the throat along the outside of the tube is permitted to expand and become turbulent for more thorough mixing with the gas throughout the length of the divergent wall section; otherwise, Where the tube terminates below the throat region the tendency is for the air to develop a back draft in the reduced pressure region of the throat.

As an alternative, the burner tube may be rigidly mounted in place on the orifice member 14 by means of a bracket 18 which may suitably take the form of an elongated rectangular, thin-walled plate 60 having a forwardly extending yoke arm 61 at its lower end with an inner concave surface 62 being inserted and clamped between one side of the orifice body and the upper circular edge of the fitting, and an upper yoke arm 64 having an inner concave surface 65 conforming to the outer periphery of the tubing 16 and being welded or otherwise permanently affixed thereto. Thus, the lower end of the bracket is clamped between the orifice body and the upper edge of the fitting to define a rigid support for the tubing 16 and insure accurate outer concentric alignment of the tubing with respect to the orifice at all times.

In practice, the kiln is heated and gradually brought up to the desired temperature level over an extended time period, perhaps several days, and in certain instances is gradually cooled under controlled conditions to a reduced temperature level, or room temperature. The heat curve or chart established will of course vary with the composition of ,the ware for optimum heat treatment, and for this purpose conventional scanning devices are employed to sense the temperature at different zones of the kiln throughout the heating operation specifically to assure that the kiln is following the predetermined temperature curve specified for the ware. If the kiln should fluctuate or vary from the given level the necessary correction may be made by regulating the gas supply, or gas pressure, to each of the burners. In accordance with the present invention, as the gas flow rate for a given pressure level changes, the air drawn into the shell for mixing and burning with the gas will correspondingly change. This results from the fact that the gas stream or flame path is directed concentrically through the burner tube in the throat region of the shell to establish maximum velocity and to most effectively induce the maximum supply of air through the throat region for mixing with the gas at all times. Stated another way, the gas stream or flame velocity is influence by the throat region and by the tube 16 to be at a maximum thereby reducing pressure in the region and encouraging upward flow of air therethrough so that under all pressure conditions an adequate air supply is available for mixing and burning with the gas. Again the flow of air through the throat will increase correspondingly with increases in the gas supply pressure.

The elongated straight wall section 30 permits the air to expand and to increase in turbulence for thorough mixing with the gas flame. Further the wall section materially aids in improving the flame pattern specifically in elongating the flame while guiding it and concentrating its heat so that it is applied to the undersurface of the kiln with minimum heat loss. According to the heat range to be established, the straight wall section should be of suflicient height to enclose the substantial length of the flame so that at maximum temperatures only the tip of the flame will project above the burner shell into direct contact with the undersurface of the kiln or other surface to be heated.

For the purpose of illustration and not limitation, kiln burners designed for heating in the range of two to twothousand-five-hundred degrees Fahrenheit are provided with a burner shell having an overall length of seven and a half inches with the length of the straight wall section,

that is, from the throat region 28 to the upper circular edge 32 being five and three-quarters inches, and the throat diameter being approximately one and one-quarter inches and the inner diameter of the base being three inches. The curved wall section 26 is formed on a one and-one-quarter inch radius to establish rapid convergence of the wall section from the base into the throat region thereby insuring rapid reduction in pressure from the base through the throat region. Again the dimensions are given merely for the purpose of illustration in a typical but preferred application of the present invention and may undergo suitable variations according to its intended application and heat requirements. It is therefore to be understood that the foregoing and other modifications may be made in the specific construction and arrangement of parts comprising the present invention without departing from the spirit thereof.

What is claimed is:

1. A gas burner for heating kilns comprising in combination a venturi-shaped shell including a base portion having a central ring with a circular opening therein and radial flanges dividing said base into spaced inlet openings, the wall of said shell converging sharply in an upward direction from the base into a restricted throat region, then diverging gradually away from the throat region to define an elongated divergent wall section, a gas supply fitting inclding an upper connecting end for insertion through the circular opening in the base of said shell ad being provided with a gas supply passage therein, an orifice member being connected to the upper end of said fitting with a discharge orifice at the upper end of said member communicating with the gas supply passage, and an elongated thin-walled burner tube having its lower end secured in surrounding relation to said orifice member with a series of longitudinal slots at spaced circumferential intervals in the wall of said tube directly above said discharge orifice, said burner tube projecting upwardy from said orifice concentrically through the throat region.

2. A gas burner according to claim 1, said convergent wall section being generally concave and being formed on a radius of curvature corresponding to the diameter of the throat region of said shell, and the diameter of the throat region of said shell being approximately one-half the diameter of said base.

3. A gas burner comprising a venturi-shaped burner shell including a base, air inlet openings at the lower end of the shell adjacent to the base, the wall of the shell converging upwardly from the base into a throat region, a gas supply passage terminating in a discharge orifice and projecting upwardly from the base, gas supply means to deliver gas under pressure to the gas supply passage and orifice, and an upstanding bracket member extending in outer spaced relation to said burner tube having a lower end rigidly attached to the base of said shell and an upper edge rigidly attached to the external surface of said burner tube.

4. A gas burner according toclaim 3, said gas supply passage being defined by a fitting projecting downwardly from the base of said shell and including an upper extension inserted through a circular opening centrally of the base of said shell, and a hollow 'body provided with the discharge orifice connected to the upper extension on said fitting.

5. A gas burner comprising a venturi-shaped burner shell including a base, air inlet openings at one end of the shell adjacent to the base, the wall of the shell converging sharply away from the base into a restricted throat portion then diverging gradually away from said throat portion to define an elongated divergent Wall section, a gas supply passage having a discharge orifice projecting from the base toward said throat portion, an elongated thin-walled burner tube having its lower end disposed in surrounding relation to said gas supply passage concentrically between said gas supply passage and said shell with a series of longitudinal slots at spaced circumferential intervals in the wall of said tube above said orifice, and said burner tube projecting upwardly from said orifice through said throat portion.

6. A gas burner according to claim 5, said burner tube terminating immediately above the narrowest region of said throat portion.

References Cited UNITED STATES PATENTS 11/1913 Chadborn 431-210 7/1914 Szocs 431-355 9/1935 Gerer 431-355 5/1938 Smith et al 431-355 3/ 1944 Ehnbom 239-417 FOREIGN PATENTS 5/ 1910 France. 1/ 1929 Great Britain. 8/ 1936 Great Britain.

EVERETT W. KIRBY, Primary Examiner US. Cl. X.R. 

